The present invention relates to an axial (radial) flow fan, and especially to a fan in which the rotary shaft and bearing are made of ceramics.
Currently, small size fans are used in the heat dissipating device of a microprocessor, and can be directly adhered to the surface of a microprocessor or firmly secured to a radiating piece so as to dissipate heat from the microprocessor or the radiating piece and thereby ensure that the microprocessor can run various softwares correctly.
The prior art small type axial (radial) flow fan includes a blade set and a fan seat. The seat has a hollow post. A copper bearing and a stainless steel bearing are arranged in the hollow post. A coil is installed outside of the hollow post. The blade set is formed with a cap and blades connected to the cap. A magnet pushed by magnetic force and a stainless steel rotary shaft supported by the two bearings is arranged within the cap. As the aforesaid coil generates a magnetic force, the magnet is pushed to cause the blades to operate and produce a wind with a wind pressure.
Since the aforesaid stainless steel rotary shaft is arranged on the copper and stainless steel bearings to rotate, after rotating for a period of time, the rotary shaft and bearing will wear and, thus, the lifetime of the fan will be reduced. Moreover, the copper bearing has a thick wall so that the inner diameter of the hollow post in the fan seat is also increased. After the inner diameter of the hollow post is increased, the outer diameter of the coil and blade set are also enlarged so that the output wind amount and wind pressure are reduced and thus the wind cannot blow to a farther place.
Furthermore, the prior art fan has many parts. Not only is the assembly and working sequences of the prior art fan complex, so that much working time is required, but the manufacturing cost is also high.
Accordingly, the primary object of the present invention is to provide an axial (radial) flow fan in which the defects in the prior art are alleviated. In the present invention, a sheath surrounding the rotary shaft and a bearing in the fan are made of ceramic material. Since the ceramic material is heat-durable and wear-tolerable, after the rotary shaft operates in the bearing for an extended period of time, no mechanical fault and no physical variation occurs so that the rotary shaft operates in the bearing.
Another object of the present invention is to provide an axial (radial) flow fan, wherein the tube wall of the bearing made of ceramics is thin. Therefore, as the fan seat is manufactured; the inner diameter of the hollow post can be reduced. Accordingly, the outer diameter of the coil and the inner diameter of the cap reduce. Not only the output wind amount increases, but also the wind pressure increases. Therefore, wind can be transferred to a farther place.
A further object of the present invention is to provide an axial (radial) flow fan, in which the assembled time and working sequences are saved, and therefore the manufacturing cost is reduced.
To achieve the above objects, an axial (radial) flow fan is disclosed. After the rotary shaft is made of ceramic material, the rotary shaft is installed with a channel passing through the body of the rotary shaft. The rotary shaft is placed in a mold. As plastic material is filled into the mold to form the blade set, the plastic material passes through the channel of the rotary shaft to extend to a free end of the rotary shaft so as to form a retaining portion, and therefore, the plastic material and rotary shaft are combined. After the bearing is made of ceramic material to have a tube shape, it is tightly arranged at the hollow post of the fan seat. Then the aforesaid rotary shaft is inserted into the bearing. The retaining portion of the rotary shaft is arranged with a fastening member or extension so that the blade set will not separate from the bearing.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when reading in conjunction with the appended drawing.